33'' tower problem {mako pd1803}

[iain/hsm]

Your not going to like this but out of interest how much did this filter cost you on Ebay, what else did you get with it? how much did you pay for postage and any extra import duty/taxes?

Depending on when you bought it from is there any mileage in talking to the seller.

While again without a photo its difficult to give advise but if the tower is 3.3/4" OD on a 0.50" wall and is black hard anodised then its made from a pre heat treated 7075 material hardened to T6 condition. There is no way you can braze or weld this material and retain temper.

The shell does have a 4:1 safety factor from the working pressure of 5000 psig (350 barg) to burst but not knowing the filter life history or pressure cycles it would be very difficult to advise anything other than scrapping out the whole assembly and putting it down to experience. Like other filters the life design is 15000 pressure cycles, 15 years working life approx

E-bay is not the best place to buy pressure vessels or compressors but is used time and time again to dump old rubbish scrap onto unsuspecting divers. One thing for certain the guy who sold you this scrap would have known.

 

[GKaplan]

Hi Phantomrfa,

Sorry i'm catching your thread so late. I'm Gabe Kaplan, Lawrence Factor New Parts Customer Support. I am not our Filters Technical Manager (Mike Casey), but he asked me to reply with a little bit of the information he would like you to know.

Therea are a few tollerances at play here. The Nipple, O-Ring, and Filter Tower Stem tollerances are all factors in how tight or lose the filter is going to be. However, as long as all three parts are within tollerance (even if the fit is loose) the filter will operate correctly. what will happen, is the O-Ring will swell up because of the pressure and create a tight seal.

I would like you to email Mike Casey (Filters Technical Manager) Directly at mcasey@lawrence-factor.com for more detailed information which will encompus all the topics discussed on this thread. He is very knowledgable and would be happy to provide some helpful information.

Thanks and Have a great Day!
gabe

 

[GKaplan]

Sorry, I replied to the wrong person.

Let me know if I can help with anything regarding technical help or otherwise in the Hi-PSI compressor industry.

Thanks!
Gabe

 

[GKaplan]

Hi Phantomrfa,

Sorry I am replying so late in the thread. I'm Gabe Kaplan with Lawrence Factor. I am having trouble replying to this thread so I will send you a message.

Have a great day!
Gabe

 

[GKaplan]

testing this thread

 

[Zodiacdiverdave]

I think you did get the right thread Gabe, he has a couple of issues here, the most serious is corrosion on the filter tower that is causing the base o-ring to leak. He needs to get a proper accessment on the damage befor moving forward.
ZDD

 

[iain/hsm]

Hi Phantomrfa,
EDITED
what will happen, is the O-Ring will swell up because of the pressure and create a tight seal. gabe

Hi Gabe.

Sorry about this but what’s all this about? I think you got it totally wrong or your posting on the wrong sort of forum LOL

Not sure what you do with 0-rings dude or what this bit about your “play tolerance” is about. But I have never heard this before until now that (I quote)

(quote) "The 0-ring “swells” up because of the pressure even if the fit is loose."

0-rings have never done that for me, but then again I’m older LOL
Can I respectfully suggest you try Penthouse LOL Iain Middlebrook

 

[iain/hsm]

phantomrfa.

As far as this problem is concerned your best option is to raise a complaint with E-bay and Pay Pal (assuming you paid that why) as the goods are faulty scrap.

Maybe to late for this advise but I would also like to know who sold you the part where it came from how long it had been in service and with that amount of neglect if this was a one off chancer using Ebay to dump scrap or a “player” who sells compressor parts.

As for the item in question. Corrosion on a 7075 alloy hard anodised tube with .5mm deep pitting over a 6mm area is cause for scrapping. Nothing else is acceptable.

The surface finish for the 0-ring groove has to be 16mu or better it is a static seal. Now while the ring deforms to effect the seal under physical compression pressure against the tube wall and the PTFE back up ring in no way does it “swell up” as other have suggested. LOL

Look also that this part is hard anodised, JB weld, epoxy and body filler will all be a total waste of time cost and effort.

The option of machining is also beyond any useful purpose unless you first remove the hard anodise facing. This will have to be stripped off first or you will burn out the carbide tooling (machining) inserts and that will be an end to your carbides.

Look again at the corrosion its likely to have gone “granular” that is it is deeper and longer than you can see, Even by removing what you can see the intergranular corrosion is a specialist field and still has no guarantee of success.

Welding or brazing will also introduce a “soft area” or a heat affected zone in the parent metal surrounding the weld. This will eventually fail under pressure and the tube will effectively split explosively.

Back to this question of tolerance.
First the thread. It’s a 3 inch by 8 TPI UN thread to a class 3 tolerance, This is a very tight tolerance say half as much again as the standard American class 2 fit used typically on there nuts and bolts. Or twice as good depending how you look at it.

The female thread inside the filter shell is also modified at the root radius to handle the rounded radius (to reduce sharpness) of the crest of the base plug and top cap.

My only real practical advise is to bring this up with Paypal and E-bay for your money back. Failing that it’s scrap and you will have to replace with new.

IMHO anything else, (apart from pure conjecture or purly for discussion) is simply impractical or beyond the capability of both yourself the various posters and most other engineering workshops. Iain Middlebrook.

 

[GKaplan]

Thanks ZodiacDiver!

Hi Phantom, Regarding your serious corrosion issue, Mike Casey is expertly knowledgable about filter systems and towers. Please email him directly for help at mcasey@lawrence-factor.com .

Thanks!
Gabe

 

[phantomrfa]

all is ok the filter tower has been tested and pass ok(ultra sound) .The rust has been removered and filled (not by me) its only in the plateing i was told. So all is fine ...